一个完整的遍历速度测试

最新推荐文章于 2025-03-27 17:30:00 发布

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#iterator #string #测试 #list #null #import

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本文通过具体示例对比了Java中ArrayList与LinkedList使用for循环及迭代器进行遍历的性能差异。实验结果显示，ArrayList在使用for循环遍历时表现更优，而LinkedList则在迭代器遍历下更具优势。

一个完整的遍历速度测试：

import java.util.Iterator; import java.util.List; import java.util.ArrayList; import java.util.LinkedList; /** * IteratorTest * @author SageZk */ public class IteratorTest { public static long testForloops(List<String> list) { long start = 0L, end = 0L; @SuppressWarnings("unused") String le = null; start = System.nanoTime(); for (int i = list.size() - 1; i >= 0; --i) { le = list.get(i); } end = System.nanoTime(); return end - start; } public static long testIterator(List<String> list) { long start = 0L, end = 0L; @SuppressWarnings("unused") String le = null; start = System.nanoTime(); Iterator<String> it = list.iterator(); while (it.hasNext()) { le = it.next(); } end = System.nanoTime(); return end - start; } public static void main(String[] args) { //测试列表长度 final int LEN = 10000; //初始化测试用数据 List<String> arraylist = new ArrayList<String>(); List<String> linkedlist = new LinkedList<String>(); for (int i = 0; i < LEN; ++i) { String s = Integer.toString(i, 2); arraylist.add(s); linkedlist.add(s); } //打印测试结果 final String FORMAT = "%1$-16s%2$-16s%3$16d/n"; System.out.println("List/t/tType/t/tTime(nanoseconds)"); System.out.println("-------------------------------------------------"); System.out.printf(FORMAT, "ArrayList", "for", testForloops(arraylist)); System.out.printf(FORMAT, "ArrayList", "Iterator", testIterator(arraylist)); System.out.printf(FORMAT, "LinkedList", "for", testForloops(linkedlist)); System.out.printf(FORMAT, "LinkedList", "Iterator", testIterator(linkedlist)); } }

以下是 3 组测试结果：

BatchFile code

List        

Type

        

Time

(

nanoseconds

)




-------------------------------------------------


ArrayList       

for

                      

1189258




ArrayList       Iterator                 

2365594




LinkedList      

for

                    

152396254




LinkedList      Iterator                 

2340801







List        

Type

        

Time

(

nanoseconds

)




-------------------------------------------------


ArrayList       

for

                      

1235701




ArrayList       Iterator                 

4249982




LinkedList      

for

                    

149825606




LinkedList      Iterator                 

2525531







List        

Type

        

Time

(

nanoseconds

)




-------------------------------------------------


ArrayList       

for

                      

1198267




ArrayList       Iterator                 

2584617




LinkedList      

for

                    

150382451




LinkedList      Iterator                 

2347994